The present invention relates to an eye fundus camera capable of effectively eliminating undesirable reflected and diffused light beams produced by the lens of the eye to be inspected, and eliminating undesired reflected and diffused light beams resulting from the interaction of the illumination light beam and the cornea of the eye to be inspected.
It is well known that when an eye to be inspected is illuminated with an illumination light beam at the time of taking a picture of the eye fundus, a part of the illumination light beam is reflected on the surface of the cornea and the lens or diffused in them. There is a possibility that the reflected and the diffused light beams become mixed with the light beam reflected on the eye fundus for photographic or the observational purpose so as to produce flair light or ghost images. It is therefore desirable that the aforementioned reflected or diffused light beams should be removed. Until now the undesired light beams reflected primarily from the surface of the cornea has effectively been removed by means of a ring illumination method. However, little interest is paid to the removal of the light beams reflected on the lens and the cornea and to the light beams diffused in the lens, which light beams are weak as compared with the light beam reflected on the surface of the cornea. However, along with the recent demand for a wide angle eye fundus camera and a clearer photograph of the eye fundus, the light beams diffused in the cornea, the light beams reflected on the lens and the light beams diffused in the lens can no longer be disregarded.
One of the means for removing the undesired light beam reflected on and diffused in the lens is disclosed by the U.S. Pat. No. 3,851,954. In accordance with this method, a black spot is provided in the illumination light beam in such a manner that the undesired reflected light beam is removed by means of the black spot and the ring-shaped aperture.